Liquid developing apparatus

ABSTRACT

Apparatus for developing diazo-sensitized copy material by the application thereto of a quantity of liquid developer includes a rotatable applicator roller to the surface of which there is supplied developer liquid, and a pair of blade members mounted adjacent the roller for engagement therewith. One of the blade members wipes excess developer liquid from the surface of the roller, and the other blade member forms a developing zone with the roller, whereby diazo material passed therethrough is developed by the application of the developer liquid.

3,704.662 Dec. 5, 1972 United States Patent Johnson et al.

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1 LIQUID DEVELOPING APPARATUS BAC KGROUND OF TIIE INVENTION This invention relates generally to apparatus for developing diazotype copy material and more particularly to apparatus of the above-mentioned type which applies a liquid developing agent in metered quantities to exposed diazo sensitized copy material, thereby to produce dry-to-the-touch developed copies.

The method of developing diazo sensitized copy material by the application of relatively small, metered quantities of liquid developer is described in U.S. Pat. No. 3,446,620, issued May 27, 1969, and assigned to the same assignee.

Apparatus for carrying out the above-described method is also disclosed in U.S. patent applications Ser. Nos. 831,685 and 831,399, assigned to the same assignee.`

In the last-mentioned applications there is described developing apparatus comprising an applicator roller which has a uniquely prepared surface adapted to receive and carry a limited quantity of developer fluid. Against the surface of the applicator roller and parallel to the axis of rotation thereof, is a mechanical wiper used for removing excess fluid from the applicator roller surface. A second, pressure applying roller is in driving engagement with the applicator roller to form a developing zone therebetween. Copy material fed between the rollers is developed by the application of the liquid under pressure provided by the pressure roller.

The apparatus of the aforementioned application operates well to provide fully developed, dry-to-thetouch copies with a minimum of developing fluid. However, in the case wherein very wide diazo copy material (i.e., in the range of 40 plus inches) is to be developed, applicator and pressure rollers must also be of lengths equal to or greater than the width of the material.

In practice a pressure roller used in the abovedescribed apparatus weighs approximately l pound for each inch of length. Thus, a roller of 40 plus inches would weigh 40 or more pounds. The great weight of such a roller member presents engineering problems in that added support is required for the roller members and greater costs for the fabrication of such an apparatus would be incurred.

In addition to the last-mentioned problems, because of the length of the rollers, irregularities in the surfaces, non-uniform pressures therebetween along the lengths ofthe rollers and/or curves in the rollers themselves which occur in fabrication or during use, might tend to produce a non-uniform application of developer fluid to copy material passing through the developing zone, resulting utimately in unacceptable, non-uniformly developed copies.

SUMMARY OF THE INVENTION Accordingly, it is a general object of the present invention to provide new and improved apparatus of the general type described for developing diazo sensitized copy material which avoids the drawbacks discussed.

It is a more specific object of the invention to provide an apparatus of the last-mentioned type which can be used successfully and efficiently in the development of relatively wide diazo sensitized copy material by applying uniformly thereto, a predetermined quantity of liquid developing agent.

Briefly, a preferred embodiment of the developing apparatus according to the invention comprises an applicator roller member adapted to carry a limited quantity of developer fluid and mounted for rotation. Ad-

5 jacent the surface of the applicator roller and extending blade and the applicator roller. A series of holes is formed in the member, from which fluid is pumped onto the metering blade member. The fluid is dispersed by the blade member over the surface of the roller, and theexcess fluid wiped from the roller surface by the fluid metering blade is carried into a trough beneath the applicator roller.

To ensure the uniform dispersion of developing fluid over the roller surface and to prevent fluid droplets from building up in the developing zone between the applicator roller surface and the pressure applying blade, provision is made to move the pressure applying blade, into engagement with the roller surface a predetermined time after engagement of the wiper blade with the roller surface; sufficiently long to meter a uniform layer of fluid onto the roller surface. The latter is accomplished automatically by means of a novel electrical circuit and control-linkage arrangement upon energization of the power switch of the developer apparatus. The blades are likewise removed sequentially from contact with the roller surface upon deenergization of the apparatus. Removal of the blades from contact with the applicator roller surface when the developing apparatus is not in use prevents marking of the roller surface by the blades which could detrimentally affect the quality of subsequent copies produced by the apparatus.

DESCRIPTION OF THE DRAWINGS A better understanding of the present invention and its organization and construction may be had by referring to the description below in conjunction with the accompanying drawings wherein:

FIG. l is a plan view of a diazotype copying machine incorporating the developing apparatus according to the invention;

FIG. 2 is a side sectional view of the copying machine of FIG. Il;

FIG. 3 is an enlarged side view of the cam driver used for moving the metering and pressure applying blades of the developing apparatus into and out of engagement with the surface of the developer fluid applicator roller taken along the line 3 3 of FIG. l; and

FIG. 4 is a schematic diagram of the electrical circuitry for operating the developer apparatus in accordance with the present invention.

DETAILED DESCRIPTION Referring now to the drawings more in detail, FIGS.

l and 2 illustrate a diazotype copying machine l0, in-v cluding developing vapparatus l2 according to the inventon.

The copying machine comprises a housing 14 including front and rear walls 16, 18, upper and lower walls 20, 22, and side walls 24, 26, interconnecting the upper, lower, front and rear walls.

A lower section 28 of the housing (FIG. 2) includes copy sheet exposure apparatus 30 for exposing a diazo sensitized copy sheet to light while the copy sheet is in surface-to-surface contact with an original tracing, for the purpose of imaging the copy sheet.

The particular copy sheet exposure apparatus shown in FIG. 2 of the drawings comprises a rotatable lamp 32 about the outer surface 34 of which is carried a sandwiched copy sheet and original tracing (not shown) for exposure of the former. An endless belt 36 extends about4 the outer surface of the lamp 32 and is also mounted forv movementalong rollers 38, 40, and 42. A

smaller roller 44 provides tension to the belt 36 to ensure that the latter is in close contact with the lamp 32.l

The sandwiched original tracing and copy'sheet are fed over shelf 45 into an entrance 46 adjacent roller 42 between b elt 36 andouter surface 34 of lamp 32. The original and copy sheet are carried about lamp 32 and depart at exit 48 adjacent roller 38. At this point the copy sheet has been exposed. The copy sheet is separated from the original tracing, and is now ready for development.

In the upper section 50 of the copying machine housing 14, there is located a preferred embodiment of the developing apparatus 12 according to the invention.

The developing apparatus l2 comprises an applicator roller 52 having a central shaft portion 54 of metal and an outer or peripheral layer 56 of a smooth nonporous, resilient material such as rubber. The outer surface 58 of the peripheral layer 56 is specially prepared to form a developer fluid carrier -surface having irregular depressions of varying depths and sizes. A more detailed description of the carrier surface will be given hereinafter.

Roller 52 is mounted for rotation at ends 60, 62 of shaft portion 54 between vertically extending walls 64, 66, in bearings 68, 70 mounted on the walls (FIG. 1).

An extension member 72, including a sprocket wheel 74 is mounted at end 62 of shaft 54. A drive motor 76 provides the power for driving the applicator roller 52 through shaft 78 extending from the gear train 79 of motor 76, and including a sprocket driveI wheel 80 mounted thereon. An endless chain 75 connected to the aforementioned sprocket wheels serves to transfer the power provided by motor 76 to the applicator roller 52 for rotation of the latter.

The chain 75 also extends about sprocket wheels 82, 84 which are'mounted on shafts 83, 85, respectively, extending from wall 66. The last'mentioned wheels provide a path overwhich endless chain 75 moves to drive applicator roller 52.

Positioned on opposite sides of roller 52, spaced 180 from each other thereabout, is a pair of blade members 86, 88, respectively. Each of the blade members 86, 88 is mounted on a respective rotatable support herein taking the form of a tubular shaft 90, 92, by means of a blade holder member 94, 96 attached thereto, respectively. The blades, each fabricated from a flat length of spring steel or the like material, are fastened to a respective blade holder member by fasteners, such as bolts 98.

The shafts 90, 92, which are also mounted between walls 64, 66 are rotatable in the direction of the arrows (FIG. 2) to cause blade members 86, 88 to engage the surface 58 of roller 52, as shown in dotted lines. As can be seen, the blade members are caused to be bowed when in contact with the roller surface to make tangential contact therewith.

A tubular conduit 100 mounted on an L shaped bracket 102, connected to blade holder member 94 is provided to dispense developer liquid to the surface 58 of roller 52. A flexible tube 104 coupled at one end 106 of dispenser tube 100 is connected via developer fluid pump 108 to a reservoirl09 of fluid developer,l10. Fluid pumped through tube 104 exits from tubular conduit 100 through spaced apertures 103 (FIG. 2) provided in the wall thereof.

Developer liquid dispensed from the tube 100 is poured onto the surface 112 of blade 86, and upon the latter making engagement with the surface of rotating roller 52, is applied or metered onto the roller surface 58.

Metering blade member 86 together with the roller 52 having the specially prepared surface 58 delivers a controlled amount of developer fluid to a copy sheet being developed. The blade member 86 wipes away excess developer fluid which in turn runs back into a trough 114 mounted'beneath the applicator roller and metering blades. The excess fluid is channeled through an opening 116 in trough 114, (FIG. 2), and through a screen-like filter lll to the fluid reservoir 109 so that it may be reused. The filter screen 111 serves to remove minute paper particles which may have found their way into the developer fluid during the development process, and which, if not removed, could eventually become lodged beneath the blade members, causing streaks along the surface of subsequently developed copy sheets. Cleaning of the filter screen 111 periodically to remove the paper particles build up thereon is desirable.

As mentioned heretofore, the surface 58 of the applicator roller 52 is specially prepared to carry a predetermined quantity of developer liquid used to develop diazo sensitized copy sheets.

The texture or finish of the applicator roller 52 is important to the successful operation of the developer apparatus. The amount of developer fluid retained on the roller surface 58 and carried to the copy sheet being developed is dependent on the surface characteristics of the roller. It has been found that the surface best suited for carrying the proper amount of liquid for development of dry-to-the-touch copy sheets is one of varying depths and sizes providing a predetermined degree of average center line smoothness expressed in terms of micro-inches in depth. lt has been concluded that an applicator roller having a center line average smoothness in the range of l0-200 micro-inches provides a satisfactory finish according to the invention. The limits of fluid application provided by a properly prepared roller surface reside between`0.5 grams and 3.0 grams per square meter of the copy material.

For a more detailed description of the roller surface and its preparation, the readers attention is directed to U.S. patent applications, Ser. Nos., 831,685 and 831,399, assigned to the same assignee.

The second blade member 88, when engaged with roller surface 58, applies to the latter surface pressure along a line'of contact therewith equal to the force applied by blade member 86, 180 about the roller 52. The contact area forms a developing zone 118, (FIG. 2) through which copy sheets are passed to be developed. r

Itis important that the forces applied to the roller surface are equal. If they are not, a tendency for the roller to shift will be prevalent as well as a possible disliguration of the surface of the roller. In both of the last-mentioned cases, the ultimate quality of copies produced in the developer will be affected.

A copy sheet entering the developing apparatusl at entrance 120 is manually urged upwardly along curved guide member 122 mounted on fixture 119 within section 50 of the housing (FIG.-2) into the developing zone 118, whereat the leading edge ofthe paper is gripped between the pressure applying blade member 88 and the roller 52. The -rotation of roller 52 in'the direction indicated by the arrow, transports the'copy sheet through zone 118 whereat developer fluid is applied in printing fashion, to the imaged copy sheet. The

developedcopy sheet emerges from the developing apparatus at exit 124in a dry-to-the-touch condition.

As mentioned heretofore, the blade members 86, 88 arel eachmounted on members 90, 92 respectively, which can be rotated to cause the engagement and disengagement of the blade members with the surface 58 of applicator roller52.

The physical movement of the blade members is controlled by a control-linkage and electrical contact assembly 126, shown in greater detail in FIGS. 3 and 4 of the drawings.

The previously mentioned assembly 126 includes a control-linkage member, preferably taking the form of a cam vmember 128 having a generally circular shape and mounted for rotation at the center 130 thereof to the shaft 132 of an electrically operated motor 134 (FIG. l) capable of being operated in a forward (engage) and reverse (release) direction by means of motor engage and release coils, respectively, to be discussed hereinafter. 1

Two sets of electrical contact arrangements 136, 138, each including two pairs of leaf spring contacts 136a, 136b and 138a,138b, respectively, are mounted, by means of insulating mounting arrangements 137, 139, respectively, of the well known type, adjacent cam member 128 at opposite sides thereof (180 about the circumference ofthe cam member). The contacts are operated by means of cam follower rollers 140, 142, connected to the stacked contacts by means f addtional leaf springs 143, 145, respectively. Each of the rollers rides along the external surface or edge 147 of the cam member 128. Lead wires as seen in FIG. 3, are connected to the terminal ends of the respective contacts. The actual connections to contacts 136a, 136b, and 138a, 1 38b will be described hereinafter when discussing the circuit diagram of FIG. 4.

The cam member is constructed to include three outer track portions, T1, T2, T3, each at a dierent, predetermined distance measured along a radius of the cam member from the center of the latter, and along which the follower rollers 140, 142 ride. As the cam member 128 is rotated, contacts of the arrangements 136, 138 are opened or closed, as the case may be, to in turn energize or deenergize motor 1514.

A pair of arms 144, 146, each of which is pivotally connected at a first end 149, 151, respectively, by fasteners 148, 150 (FIGS. 1 and 3) to a respective end 152, 154 (FIG. 1) of one of the rotatable tubular shafts 90, 92, is provided to translate the rotatable movement of the cam member 128 into a driving force for movement of the blade members 86, 88. The opposite ends 156, 158 of arms 144, 146 are each coupled by a cam follower wheel or roller 160, 162 respectively,'to cam member 128. The last-mentioned wheels being mounted for rolling engagement in specially designed cut-outs or tracks 164, 166 in cam member 128. Each of the tracks 164, 166 includes a passive track portion Pl, P2 and an active portion A1, A2, respectively. Movement of the rollers 160, 162 along the passive portions of the tracks 164, 166, causes no physical movement of the respective blade members, and movement in the active portions of tracks 164, 166. ca uses the blades to be moved into or out of engagement with the applicator roller surface 58, depending upon the direction of rotation (clockwise or counterclockwise) of cam member 128. The operation of the cam member 128 and followers will be explained hereinafter.

Turning now to FIG. 4 of the drawings, there is illustrated therein a preferred embodiment of the circuit for controlling the movement of the blade members 86, 88 into and out of engagement with the applicator roller 52.

The circuit 170 is powered by a convention 115 volt AC source, (not shown) connected across terminals 172, 174 each of which is in turn connected to a lead 176, 178, respectively. Lead 176 is connected to a first armature 180 of the manual operated on-off switch 182. Switch armature 180 is normally connected to a first contact 184 which is in turn connected to a lead wire 186. The last mentioned wire 186, is connected to normally open contacts 138a of leaf contact spring pair 138.

A second contact 188 of the manual on-off switch 180 is provided for connection with armature 180. The movement of armature 180 to contact 188 supplies power via lead 183 to operate pump motor 108, thereby to begin pumping fluid to the tube member 100 (FIG. l) and to begin the movement of blades 86, 88. Pump motor 108 is connected back to the power source via lead 178. The movement of switch arm 180 t0 contact 188 also provides power from the source to energize drive motor 76 for rotating applicatorv roller 52.

The contacts 13811, connected to manual on-off switch 182 via lead 186, are connected via lead 192 to motor release coil 190 of motor 134 which in turn is connected through leads 194, 196, back to the AC power source.

The contacts l38a are also connected to a second armature 198 of manually operated on-off switch 182. The armature 198 is normally in the open position with respect to contact terminal 200 of the switch. The lastmentioned contact terminal is connected via lead wire 202 through switch contacts 136b of contact pair 136, via lead 204 to the normally closed sets of contacts 206 of a three second time delay relay 2108. The armature 207 of relay 208 is connected backv to switch contact 188 of switch 182 via lead 209.

The normally open contacts 210 of relay 208 are connected via lead 212, through normally closed conlast-mentioned coil is connected back to the power source via leads 196, 178. A

Normally closed contacts 138b arev connected also via lead 218 through normally closed contacts 136a of 5 contact pair 136, and leads 220 and 204 to the normally closed contacts 206 of time delay relay 208.

For purposes of affording a more complete understandng of the invention, it is advantageous now to provide a functional description of the mode in which the component parts thus far described cooperate.

Looking again at FIG. 4, the circuit 170 as it appears, is in the unoperated, normal state. When it is desired to operate the developer apparatus of the invention, the manual on-off switch 182 is'depressed, causing armature 180 thereof to be moved from contact 184 to contact188, opening the connection to lead 186 and closing operating circuits to pump motor 108 drive'motor 76 and a circuit via lead 209- and the normally closed contacts 206 of time delay relay 208.

At-this time lapplicator roller 52 starts to rotate and fluid begins to be pumped'from the'reservo'ir 110l to tube 100 for distribution onto blade 86 and over the surfacevof the applicator roller.

Power lis applied through the .normally closed contacts of relay 208, via lead 204 through lead 220 and normally closed contacts 136a and leads 218 and 214 to the motor engage coil 216 to begin rotation of cam 128 in the direction arrow 224 (FIG. 3). The cam is rotated approximately 40 in the counterclockwise direction as seen in FIG. 3 to an intermediate position. As the cam turns, rollers 140, 142 roll along the edge 147 thereof.

Roller 140 remains on the track T1 for a time but then moves to track T2, whereby contact 136a is caused to be opened. The opening of switch 136a (FIG. 4) deenergizes the engage coil 216 to stop the rotation of cam 128. At this time switch contacts 136a, 136b are both in an open condition since roller 140 is at rest on track T2. The roller 142 also moves from the track T3 to T2, and causes contacts 138a to be closed. At this time both contacts 138a, 138b are in a closed condition.

During the forty degree rotation of cam 128, rollers 160 and 162 also were moved along respective cut-outs 164, 166 in cam 128. Roller 160 moved along the passive portion P1 of cut-out 164 while roller 162 moved along the active portion A2 of cut-out 166; thus, developer fluid metering blade 86, FIG. 1, is brought into engagement with the applicator roller surface.

During the 3-second delay time of relay 208, developer fluid flowing from apertures 103 in feed tube 100, is metered over the surface 58 of roller 52. After the three second delay time is completed, relay armature 207, moves from normally closed contact 206 to normally open contact 210. Power from the 115 volt AC source now is provided again through closed contacts 138b to motor engage coil 216, once again to cause the rotation of cam member 128 in the direction (counterclockwise) of arrow 224 (FIG. 3).

The c am member 128 this time rotates an additional 80-from its intermediate position. During the 80- rotation, roller 142 moves from v track T2 to track T1, whereby switch contacts l38b are opened.

The opening of contacts 138b breaks the connection from the power source to the engage coil 216, deenergizing motor 134 and stopping the rotation of cam member 128.

During the last-mentioned eighty degree rotation of cam member 128, roller 162 was moved through the passive portion P2 of cut-out 166, so that no additional movement of blade member 86 was effected. Roller 160, however, was moved through the active portion A1 of cut-out 164, causing the pressure applying blade member 88 to be moved into engagement with the surface of applicator 52.

Once both blades are in engagement with the rotating applicator roller, the developing apparatus is deemed to be in a running condition, and diazo copies may be fed through the developer section 50 of the diazo copying machine 10 (FIG. 2) for processing.

Upon completion of the developing process, the developing apparatus is restored to its normal unoperat'ed` state by operation of the manual on-off switch 182 to its off position. ln doing so, armature 180 of the switch is moved from engagement with contact 188 into engagement with contact 184, and armature 198 thereof is moved out yof engagement with contact 200.

A connection is now made from the 115 volt AC source to motor release coil 190. The connection is from the source via leads '176, 186, through contacts 138a which remain closed because of the position of roller 142 on the track T1, and lead 192. With motor release coil 190 energized, motor 134 (FIG. 1) is operated to rotate cam member 128 in a clockwise direction opposite to the direction indicated by arrow 224. The cam is rotated a full 120 back t0 the home or normal position.

During the last-described rotation, blade members 86, 88 are sequentially removed from engagement with the applicator roller, blade member 88 being disengaged first, followed by blade member 86. This movement occurs because of the movement of rollers 160, 162 through the active and passive portions of the respective cut-outs in reverse order from that explained for the initial operating cycle.

Once returned to the home position, contacts 138a are opened to stop the motor-134, and pump motor 108 is operated to an off condition.

While the preferred means for moving the blade members 86, 88 into and out of engagement with the applicator roller 52 are the cam and circuit arrangement described above, it will be understood that such sequential movement could be obtained by other means, such as, for example, a series of gears arranged to control the movement of the blade members with a time delay arrangement operating the drive mechanism for the gears. It is therefore contemplated to cover by the present application any such equivalent means.

It has been explained that a preferred developing apparatus according to the invention includes means for moving the blade members 86, 88 into and out of engagement with the applicator roller sequentially as described. Such sequential movement is important since it affords a uniform wetting of the applicator roller prior to bringing the pressure applying blade member into contact with the roller, thereby to allow for a faster starting time as well as to prevent contact of the blade member against a relatively dry roller surface which might have a detrimental effect thereon.

While it is preferred in the subject apparatus to move the pressure applying and wiper blade members toward and away from the applicator roller, the result achieved thereby can also be achieved through movement of the roller toward and away from the blade members, as well as through the movement of both the blades members and the roller toward and away from each other.

What we claim is:

l. Apparatus for developing sensitized sheet material by the application to said material of an amount of developer liquid, said apparatus comprising:

an applicator roller mounted for rotation in a predetermined direction, said roller having a surface adapted to carry a quantity of developer liquid,

a first blade member mounted adjacent said rolle'r for engagement with said roller'. surface tol form a developing zone along a line of contact therebetween, through which sheet material is passed for development,

a second blade member also mounted adjacent said roller for engagement with said roller surface, said last-mentioned blade member being upstream of said first blade member for the purpose of applying a quantity of developer liquid to said roller surface and of wiping excess liquid from the roller surface prior to said surface reaching the developing zone, said first and second blade members being movable into and out of engagement with said roller surface, and

means for supplying developer liquid to said second blade member, said developer liquid being distributed uniformly over said roller surface by the contact of said second blade member against said roller surface.

2. Apparatus as claimed in claim 1 wherein said blade members are positioned with respect to said roller so as to equalize the forces applied thereto.

3. Apparatus as claimed in claim l wherein said blade members are located at positions spaced from each other l 80 about the circumference of said roller.

4. Apparatus as claimed in claim l wherein said means for supplying developer liquid to said second blade member includes a hollow member having apertures therein, a reservoir of developer liquid in communication with said hollow member and pump means for pumping developer liquid from said reservoir to said hollow member, whereby developer liquid is dispensed from the apertures in the last-mentioned member for application to said second blade member.

5. Apparatus for developing sensitized sheet material by the application to said material of a predetermined amount of developer liquid, said apparatus comprising:

a liquid applicator roller mounted for rotation in a predetermined direction, said roller having a surface adapted to carry a predetermined quantity of developer liquid,

a pressure applying means including a first flat,

resilient, elongated blade member mounted adjacent and extending the length of said roller, for tangential contact with the surface thereof, to form a developing zone therebetween through which sheet material is passed for development by the apiplication of developer li uid thereto, a secon resilient, elongated bla e member mounted adjacent and extending the length of said roller, for tangential contact therewith, said second blade member being located upstream of said developing zone for applying a quantity of developer liquid to said roller surface and for wiping excess liquid developer from the applicator roller surface prior to said surface reaching the developing zone, said first and second blade members being movable into and out of engagement with said roller surface, and

means for supplying developer liquid to said second blade member including a dispensing tube mounted adjacent said second blade member and having a plurality of apertures therein from which developer liquid exits toward said second blade member, whereby said developer liquid is uniformly distributed over said roller surface by the wiping action of said second blade member thereagainst.

6. Apparatus as claimed in claim 5 wherein said first blade member and said second blade member are mounted at opposite ends of a preselected diameter of said applicator roller, thereabout with respect to each other, so as to equalize the forces applied by said blade members against said roller surface.

7. Apparatus as claimed in claim 5 further including a source of developer liquid and pump means for pumping liquid from said source to said dispensing tube, and an overflow receptacle mounted beneath said roller and being in communication with said liquid source, for receiving excess developer liquid wiped from said roller surface, and returning said liquid to said source.

8. Apparatus as claimed in claim 7 further including filter means located between said overflow receptacle and said developer liquid source, for removing foreign particles and the like from said excess developer liquid prior to returning said liquid to said source.

9. Apparatus as claimed in claim 5 wherein said first and second blade members are sequentially movable into and out of engagement with said roller surface, said second blade member being movable into engagement with said roller surface a predetermined period of time subsequent to the initiation of the operation of said developing apparatus and said first blade member being movable into engagement with said roller surface a predetermined period of time subsequent to the engagement of said roller surface by said second blade member.

l l# it l# 

1. Apparatus for developing sensitized sheet material by the application to said material of an amount of developer liquid, said apparatus comprising: an applicator roller mounted for rotation in a predetermined direction, said roller having a surface adapted to carry a quantity of developer liquid, a first blade member mounted adjacent said roller for engagement with said roller surface to form a developing zone along a line of contact therebetween, through which sheet material is passed for development, a second blade member also mounted adjacent said roller for engagement with said roller surface, said last-mentioned blade member being upstream of said first blade member for the purpose of applying a quantity of developer liquid to said roller surface and of wiping excess liquid from the roller surface prior to said surface reaching the developing zone, said first and second blade members being movable into and out of engagement with said roller surface, and means for supplying developer liquid to said second blade member, said developer liquid being distributed uniformly over said roller surface by the contact of said second blade member against said roller surface.
 2. Apparatus as claimed in claim 1 wherein said blade members are positioned with respect to said roller so as to equalize the forces applied thereto.
 3. Apparatus as claimed in claim 1 wherein said blade members are located at positions spaced from each other 180* about the circumference of said roller.
 4. Apparatus as claimed in claim 1 wherein said means for supplying developer liquid to said second blade member includes a hollow member having apertures therein, a reservoir of developer liquid in communication with said hollow member and pump means for pumping developer liquid from said reservoir to said hollow member, whereby developer liquid is dispensed from the apertures in the last-mentioned member for application to said second blade member.
 5. Apparatus for developing sensitized sheet material by the application to said material of a predetermined amount of developer liquid, said apparatus comprising: a liquid applicator roller mounted for rotation in a predetermined direction, said roller having a surface adapted to carry a predetermined quantity of developer liquid, a pressure applying means including a first flat, resilient, elongated blade member mounted adjacent and extending the length of said roller, for tangential contact with the surface thereof, to form a developing zone therebetween through which sheet material is passed for development by the application of developer liquid thereto, a second resilient, elongated blade member mounted adjacent and extending the length of said roller, for tangential contact therewith, said second blade member being located upstream of said developing zone for applying a quantity of developer liquid to said roller surface and for wiping excess liquid developer from the applicator roller surface prior to said surface reaching the developing zone, said first and second blade members being movable into and out of engagement with said roller surface, and means for supplying developer liquid to said second blade member including a dispensing tube mounted adjacent said second blade member and having a plurality of apertures therein from which developer liquid exits toward said second blade member, whereby said developer liquid is uniformly distributed over said roller surface by the wiping action of said second blade member thereagainst.
 6. Apparatus aS claimed in claim 5 wherein said first blade member and said second blade member are mounted at opposite ends of a preselected diameter of said applicator roller, 180* thereabout with respect to each other, so as to equalize the forces applied by said blade members against said roller surface.
 7. Apparatus as claimed in claim 5 further including a source of developer liquid and pump means for pumping liquid from said source to said dispensing tube, and an overflow receptacle mounted beneath said roller and being in communication with said liquid source, for receiving excess developer liquid wiped from said roller surface, and returning said liquid to said source.
 8. Apparatus as claimed in claim 7 further including filter means located between said overflow receptacle and said developer liquid source, for removing foreign particles and the like from said excess developer liquid prior to returning said liquid to said source.
 9. Apparatus as claimed in claim 5 wherein said first and second blade members are sequentially movable into and out of engagement with said roller surface, said second blade member being movable into engagement with said roller surface a predetermined period of time subsequent to the initiation of the operation of said developing apparatus and said first blade member being movable into engagement with said roller surface a predetermined period of time subsequent to the engagement of said roller surface by said second blade member. 